Foliar spray agent for protecting agricultural and horticultural plants against disease injury

ABSTRACT

A foliar spray agent containing an alkali metal silicate as an active ingredient protects agricultural and horticultural plants from disease injury by spraying on the leaves of plants. Treatment of agricultural and horticultural plants with the agent provides an increase in crop yields with high quality.

FIELD OF THE INVENTION

The present invention relates to a foliar spray agent for protectingagricultural and horticultural plants from disease injury whichcomprises a alkali metal silicate as an active ingredient, and a methodof protecting agricultural and horticultural plants against diseaseinjury using said agent.

The agent of the invention protects various agricultural andhorticultural plants effectively from disease injury by using a naturalingredient harmless to human and animals, without any crop contaminationusually caused by conventional synthetic organic pesticides, andprovides a striking increase in crop yield.

BACKGROUND OF THE INVENTION

There has been described (Eiichi Takahashi, "Silicic acid plant and limeplant--investigating properties of the plants" published by incorporatedcultural association of agricultural, industrial and fishing village) anattempt to increase the yield of rice by adding approximately 100 ppm ofsilicic acid as a nutrient (fertilizer) to a culture solution to allowthe roots of rice plants to absorb it.

It has never been known hitherto, however, that pathogens can be killedby spraying an aqueous solution of an alkali metal silicate on thesurface of leaves of various agricultural and horticultural plants.

PROBLEMS TO BE SOLVED BY THE INVENTION

In recent years, pesticide contamination on various agricultural andhorticultural crops has become an issue, and recent studies has focusedon a cultivation without using conventional chemical pesticides.

It is therefore an object of the present invention to provide a foliarspray agent containing an alkali metal silicate harmless to human andanimals, as an active ingredient, for protecting agricultural andhorticultural plants against disease injury and a method for protectingthese plants against disease injury.

SUMMARY OF THE INVENTION

The present invention relates to:

(1) a foliar spray agent for protecting agricultural and horticulturalplants against disease injury which comprises an alkali metal silicateas an active ingredient, and

(2) a method for protecting agricultural and horticultural plantsagainst disease injury which comprises spraying an aqueous solutioncomprising an alkali metal silicate as an active ingredient on thesurface of leaves of the agricultural and horticultural plants.

The alkali metal silicates used in the present invention include Na₂SiO₃, Na₄ SiO₄, Na₂ Si₂ O₅, Na₂ Si₄ O₄, K₂ SiO₃, KHSi₂ O₅, K₂ Si₄ O₉.H₂O and the like, alone or in combinations thereof. Suitable examples areliquid potassium silicate from Nippon Liquid Fertilizer Co., Ltd. (K₂ O6.0% SiO₂ 25%) and liquid sodium silicate from Nippon Soda Co., Ltd.(specific gravity 41.5, molar ratio 3.12, silicon dioxide 28.47, sodiumoxide 9.42).

The foliar spray agent of the present invention is usually formulated asa concentrated stock solution and is appropriately diluted with waterbefore use.

During formulation, conventional auxiliary agents such as stabilizers orspreader for achieving effective adhesion of the agent on foliarsurfaces may be added, and other agricultural chemicals may also beincorporated in order to ensure the effect of the agent or to expand theapplication range of the agent of the invention.

The concentrated stock solution is diluted with water to containapproximately 0.006 mg˜0.025 mg/ml alkali metal silicate, and sprayeduniformly on entire foliar surfaces of plants.

The foliar spray agent of the present invention has been applied tovarious agricultural and horticultural plants such as, rice, potatoes,cucumbers, watermelons, tomatoes, strawberrys, pears, peaches, grapesand the like, and has proved to be remarkably effective in killing thepathogens, resulting in considerable increase in the crop yields.

EFFECT OF THE INVENTION

The foliar spray agent of the present invention showed an excellentprotection of agricultural and horticultural plants from disease injury.

Since the active ingredient alkali metal silicate is a natural componentwith no harm to human and animals, it can be applied safely without anydisadvantageous contamination as caused by conventional syntheticorganic pesticides.

Consequently, it is expected that a great contribution will be made bythe present invention to the agricultural and horticultural industry.

EXAMPLE

The following examples illustrate the present invention. All parts areby weight unless otherwise stated.

EXAMPLE 1 Preparation of foliar spray agent stock solution

60 parts of liquid potassium silicate (note 1), 35 parts of liquidsodium silicate (note 2), 0.5 parts of EDTA.Fe salt, 1 part of EDTA.Mgsalt, 2 parts of citric acid and 100 parts of water were mixed uniformlyto give a foliar spraying agent stock solution.

The stock solution can be diluted up to about 1000 times with water. Thediluted solution can be sprayed on foliar surfaces of variousagricultural and horticultural plants to protect them effectivelyagainst diseases. An increased crop yield can then be attained.

Note 1:

Nippon Liquid Fertilizer Co., Ltd., containing 6.0% K₂ O and 25% SiO₂.

Note 2:

Nippon Soda Co., Ltd., containing 9.4% Na and 28.47% SiO₂, and diluted1:2000.

EXAMPLE 2 Protection test on rice from blast

A paddy field of 900 m² was divided into three plots, the first plot fortreatment with no pesticide, the second plot with commercially availablepesticides, and the third plot with the spray agent of the presentinvention. Rice seedlings were transplanted into each plot byconventional method. On day 50, 70 and 95 after transplantation, thepesticides were sprayed. The occurrence of spontaneous blast wasdetermined on day 20 after each treatment on each plot (in June, July,August: three times). The blast occurrence (%) was calculated accordingto the following equation in order to evaluate the effectiveness of thepesticides. ##EQU1## A: the number of leaves showing apparent blastspots, B: the total number of leaves tested.

The above described test was repeated 3 times, in 1987, 1988, and 1989,using the pesticides indicated.

In the plot for the spray agent of the present invention, the stocksolution prepared in Example 1 was diluted 1:1000 with water and sprayedon foliar surfaces at 0.025 ml/m². In the plot for the commerciallyavailable pesticides, Fujiwan emulsion from Nippon Pesticide Co., Ltd.was diluted 1:100 with water and sprayed on foliar surfaces at 0.020ml/m². For fertilization, conventional compound fertilizer was appliedequally to each plot at 33 g/m² on May 5.

Results of this test are shown in Table 1.

                  TABLE 1                                                         ______________________________________                                                 Blast occurence (%) in each plot treated                                      with the spray agent of:                                                                    commercially                                                      the present available                                              Evaluation invention   pesticide  Control                                     ______________________________________                                        June, 1987 5            5         10                                          July, 1987 2            6         18                                          August, 1987                                                                             0           10         22                                          June, 1988 4            8         15                                          July, 1988 3           16         22                                          August, 1988                                                                             0           20         26                                          June, 1989 6            9         17                                          July, 1989 4           21         23                                          August, 1990                                                                             0           20         28                                          ______________________________________                                    

EXAMPLE 3 Protection test on cherry tomato from disease injury

2,400 of cherry tomato seedlings were transplanted to 900 m² greenhouse.The stock solution prepared as in Example 1 was diluted 1:1000 withwater and 4000 l of the diluted solution was sprayed on foliar surfacesof the cherry tomato seedlings on day 30 after transplantation. Afterthe first treatment, the treatment was repeated every 10 days withincreasing the amount of the agent with the growth of the cherrytomatoes. The seedlings were treated 12 times in total and the totalamount of the diluted solution used reached 48,000 l. During thecultivation, Kuminhosuka (manufactured by Nissan Chemical IndustrialCompany) was applied to each plot as a basal fertilizer (40 kg N, 45 kgP and 40 kg K per 10 ares) on Mar. 20.

During this cultivation, no cherry tomato was infected with pathogens.The very good growth of the plants was observed and high qualitytomatoes could be harvested until around Oct. 15th. The total yieldamounted 20 tons.

In contrast, cherry tomatoes which were cultivated analogously butwithout the pesticide of the present invention were infected with thepathogens such as gray mold, downy mildew, powdery mildew and the like.The plant growth and fruit quality of them were distinctly inferior, andthe harvesting period was shorter and the total yield was only 8 tons.

As evident from the above observation, commercially valuable cherrytomatoes can be obtained in high quality and in high yield using theagent of the present invention.

What is claimed is:
 1. A method for protecting a plant against diseaseinjury induced by a plant pathogen which comprises spraying the foliarsurface of the plant with an aqueous solution consisting essentially offrom about 0.006 mg/ml to about 0.025 mg/ml of an alkali metal silicateas the effective ingredient.
 2. The method of claim 1 wherein the alkalimetal silicate is a sodium or potassium alkali metal silicate or acombination thereof.
 3. The method of claim 2 wherein the alkali metalsilicate is selected from the group consisting of Na₂ SiO₃, Na₄ SiO₄,Na₂ Si₂ O₅, Na₂ Si₄ O₄, K₂ SiO₃, KHSi₂ O₅, K₂ Si₄ O₂ -H₂ O or acombination thereof.